Evidence of cumulate crystallization and local development of the eclogite-facies metamorphism in the olivine gabbro of the Marun-Keu complex, Polar Urals, Russia

Abstract

The paper presents the results of a detailed petrological study of olivine gabbro transformed to different extent by eclogite-facies metamorphism. Textural features of cumulate crystallization in the rock are presented. Plagioclases underwent the greatest alteration and replaced by finegrained aggregate during eclogite-facies metamorphism. Corona textures are developed along the boundaries of the plagioclase (felscic) domains at the contacts with (Fe,Mg)-minerals during eclogite facies event. The mineral thermobarometry and phase equilibrium modeling provide P-T metamorphic conditions in relatively narrow range of temperature 680±60 ᵒC and pressure Р=2,2±0.4 GPa. This is in a good agreement with the previously established conditions for the formation of eclogites and garnet-amphibole peridotite from the same complex.